The N+4th Southern California Topology Conference

Saturday January 17th, 2009

Map of campus is available here


There is free parking in the Caltech lots on weekends. A complete map of the lots can be found here. There is also parking on the street, mainly on California or on Arden.


If you need a hotel, the Saga is close and cheap.

Getting to Pasadena by air:

We encourage people from outside Southern California to attend, especially graduate students. The most convenient airport is Burbank, but LAX has more flights. For Northern California folks, Southwest has frequent service from Oakland, San Jose, and Sacramento to Burbank. Ontario and Long Beach airports are also reasonable choices, but ground transit from them to Pasadena is more expensive. For all airports, you can use SuperShuttle to get to Pasadena (about $20 one-way for Burbank, $30 for LAX and $50 + for the other two).


Some travel and accomodation support is (expected to be) available for graduate students (especially those coming from Northern California). Please contact Danny Calegari by email (dannyc at and have your advisor send a brief (1 or 2 paragraphs) email of reference (principally to justify funding to the NSF).

Coffee and donuts available outside 151 Sloan, 9:30-10:30 am

Schedule of talks:

Speaker Time Room Title
Ian Agol, UC Berkeley 10:30-11:30 am 151 Sloan LERF and virtual fibering
Steve Ferry, Rutgers 1:30-2:30 pm 151 Sloan Higson compactifications
Kevin Whyte, UIC 2:45-3:45 pm 151 Sloan Virtual Betti numbers of random complexes
Chris Leininger, UIUC 4-5 pm 151 Sloan Strong Tits alternative for pure braid groups

Abstracts of talks:

Ian Agol. Title: LERF and virtual fibering
Abstract: We show that a Haken hyperbolic 3-manifold with LERF fundamental group is virtually fibered.

Steve Ferry. Title: Higson compactifications
Abstract: We will show how volume growth in a manifold M can be used to detect cohomology in its Higson compactification.

Kevin Whyte. Title: Virtual Betti numbers of random complexes
Abstract: We will discuss bounds on the Betti numbers of finite covers of complexes under local geometric assumptions, with applications to various models of random complexes.

Chris Leininger. Title: Strong Tits alternative for pure braid groups
Abstract: A group satisfies the "Tits alternative" if every subgroup is either virtually solvable or contains a nonabelian free group. This is named after J. Tits who proved that all finitely generated linear groups enjoy this property. The Tits alternative was established for braid groups by Ivanov and McCarthy, but now also follows from linearity (due to Bigelow-Krammer). I'll discuss joint work with D. Margalit, in which we prove a strong version of the Tits alternative for the pure braid groups: every two elements of the pure braid group either commute or generate a free group. The proof uses 3-manifold topology and actions on trees.

Recreational activities:

Party at Chez Calegari (details to follow . . .) Food courtesy of Francis Bonahon and Erica Flapan.